Method of heating underground formations



Oct. 1, 1963 MPRA-rs ETAL 3,105,545

METHOD OF HEATING UNDERGROUND FORMATIONS Filed Nov. 2l, 19604 INVENTORS:

M. PRATS D. G. RUSSELL BWHHJQQW THEIR AGENT United States Patent O 3,105,545 METHOD OF HEATING UNDERGRGUND FRMATIONS Michael Prats, Houston, and Donald G. Russell, Bellaire,

Tex., assignors to Shell Oil Company, New York, NX.,

a corporation of Delaware Filed Nov. 21, 1960, Ser. No. 70,536 8 Claims. (Cl. 166-39) This invention relates to the heating of underground formations and pertains more particularly to the heating of hydrocarbon-bearing formations which are traversed by a plurality of wells.

ln many oil fields yand in most deposits of oil shales and tar sands, the oil or hydrocarbon present is often viscous or is so intimately Vheld by the sand particles or by the formation that it is impossible to produce the hydrocarbon materials merely by drilling wells through or into the deposits as is done with ordinary oil fields. Various methods have been employed in an attempt to recover certain viscous oils from underground formations with varying success being achieved with such methods as ooding with solvents, creating an underground combustion Zone, etc. Combustion of oil shale deposits has also been tried but the more general method has been to mine the shale, pulverize it and then recover the oil from the pulverized shale.

lt is an object of the present invention to provide a novel method of heating an underground formation surrounding a well borehole to some distance therefrom for reducing the viscosity of a heavy hydrocarbon so that it will be driven to and produced from another well.

A further object of the present invention is to provide a method of heating an underground formation in communication -with a hydrocarbon-bearing formation to provide partial distillation of the hydrocarbon to increase further the pressure in the formation.

Another object of the present invention is to provide a method for heating an underground formation in order to stimulate flow of oil `from depleted elds so that it will be driven to adjacent wells where it can be readily produced.

Still another object of the present invention is to provide a method for heating an underground formation for reducing the viscosity of the oil present in the formation while at the same time providing partial gasification of the residual oil in the formation.

These and other objects of this invention will be understood from the following description taken with reference to the drawing, wherein:

FIGURE 1 is a diagrammatic view of a Well taken in cross-section wherein the hydrocarbon-producing for-mation has been fractured prior to installing the heating equipment;

FIGURE 2 is a diagrammatic View of a longitudinal section of a well for producing fluids driven into the well from the heat-generating wells of FIGURES 1 and 3; and,

FIGURE 3 is a diagrammatic view of a longitudinal section of another heating well wherein the producing formation has a plurality of directionally drilled holes in it.

Referring to FIGURE 1 of the drawing, a well is shown in which a well casing 11 has been installed which extends down into the hydrocarbon-producing formation 12. The portion of the Well casing 11 that extends into the producing formation 12 is provided .with a series of .perforations 13 which may extend through the wall of the casing in all directions or in only one direction. The top of the well casing 11 is closed by any suitable well closure means schematically represented by Ka plate 14. Extending downwardly through the plate closure 14 to a point within the producing for-mation 12 of the well are a pair of concenice tric pipe strings 15 and 16. The innermost pipe string 15 is open at the lower end thereof -wlhile the outermost pipe string 16 has a closed lower end. Thus, it will be seen that the concentric pipe strings 15 and 16 provide means whereby a heating fluid may be circulated down to the bottom of the well and up to the surface again. The circulation is preferably down through the annulus between the inner mid outer strings 15 and 16 with the flow of fluid returning up through the inner string 15 as indicated by the arrows. Thus, when hot water or another fluid is circulated through the pipe strings 15 and 16 a heater is provided in the well opposite the producing zone 12.

Prior to installing the pipe strings 15 and 16, the producing formation 12, was fractured in any manner well known to the art so as to provide a series of radiallyextending fractures 17 which extend into the producing ormation 12 some distance from the well. These fractures 17 may be either horizontal or vertical type fractures. After the fractures 17 4were opened, a iiuid containing particles of a highly heat-conductive material was pumped down the well and into the fracture 17. The particle-carrying liuid is 0f any suitable type which will pass readily into the producing formation 12 leaving the particles behind to lill the fracture 17. The amount of particle-carrying iiuid which is pumped into the fracture is preferably selected so that the particles |are packed together in intimate heat-transferring contact with each other. Freferably the carrying yfluid used is a hydrocarbon fluid, but water may be employed if desired. After the fractures 17 have been filled with the particles of heatconductive material, the heating apparatus comprising the pipe strings 15 and 16 are installed in the well. In a preferred arrangement a sufficient volume of additional heatconductive material is circulated or dumped down the well to fill the well, as :at 1S, preferably to at least the top of the producing formation 12 to be heated.

rThe particles of material which are packed around the outside of the lower end of the pipe string heater 16 and which fill the fractures 17 are preferably a fluid-transportable form of aluminum, copper, or some other metallic material which has a thermal conductivity greater than that of the formation which is to be heated. By extending the body of material of increased heat conductivity into the formation by means of the fractures 17, an increase in the rate of heat transfer from the heat source 16 into the formation 12 takes place. The amount of the increase that takes place in the rate at which heat is transferred to the formation, increases as larger amounts of metal are :inserted into the formation. lt is preferable but not essential that each portion of the metal be placed in intimate heat-transferring contact with the adjacent portions. Small flakes of metal foil or particles of soft metal which are pressed together as the .fractures subside are particularly effective. Relatively low-melting metallic materials which fuse together nat the temperatures of the 'heating operation are also particularly effective.

Fluid surrounding the well of FIGURE 1, when heated, would be driven to an adjacent producing well illustrated schematically in FIGURE 2 as comprising a well casing 21 having perforations 22 near the lower end thereof in the section of the casing that traverses the producing formation 12. Extending down through the casing 21 is a production tubing string 23 having a pump of any suitable type secured to the lower end thereof. The pump 24 may be actuated, as by a string of sucker rods 25 which is reciprocated by a conventional prime mover 26.

In another well installation in which the method of the present invention may be practiced, a well casing 31 (FIGURE 3) is shown as lining a well with -a pair of side windows 32 Iand 33 having been milled or otherwise 3 7 cut through fthe side Wall of the casing 31. Side holes 34 and 35 are then drilled through the milled holes 32 and 33 in a conventional manner so as to provide holes which extend into the producing formation 12 for a substantial distance from the well. These holes 34 and 35 are then lled with particles of a material of high conductivity in the same manner as described hereinabove with regard to FIGURE 1. However, if the angle of the holes 34 and 35 is sufficient, the granular or particulate material of high conductivity may be dumped down the well and into the side holes 34 and 35 rather than circulating it in place by means of a uid. ilf desired, however, a carrying fluid may be employed as described with regard to FIGURE 1.

Prior to or after the holes 34 and 3S have been filled with the particulate material of high conductivity, a suitable heater, for exmple an electric heater 37' is lowered down through the well casing 3l by means of a weight-supporting and current-transmitting cable S3, the heater 37 being suspended on its cable 3S from the top 39 of the well with the heater being positioned at the level of the producing formation 12. With the heater 37 in place the well casing can be filled with the heat-conductive material to a point above the heater 37. Power would be supplied to the heater through a power lead 4t?.

The well, arranged as shown in FIGURE 3, may be to heat the oil contained in the surrounding formation and drive the heated oil toward a producing well such as Ithe one shown in FIGURE 2. Alternatively, the well shown in FIGURE 3 may be perforated above the zone containing the heater and completed by installing a pump such as pump 24 (FIGURE 2) within the well opposite the upper perforated zone. In this latter arrangement, particularly where the temperatures employed are sufficient to pyrolyze the oil contained in the surrounding form-ation, the fluidized hydrocarbons are driven into the perforated zone of the Wall by the localized relatively high pressures which are thermally induced within the formation around the well.

The method for heating an underground oil-bearing formation described hereinabove gives an improved rate of heat transfer from a heat source to the formation where the heat transfer is accomplished by conduction through the formation. While the method has been illustrated with regard to fracturing or direotionally drilling the producing formation to create channels which extend outwardly from a well into the producing formation, it is to be understood that other types of fractures, crevices or holes may be employed including those which occur naturally so long as they extend laterally from the well into the producing formation.

We claim as our invention:

1. A method of heating `a hydrocarbon-bearing earth formation for the purpose of producing a hydrocarbon fluid therefrom, said method comprising the steps of establishing communication between the hydrocarbon-bearing formation and the ground `surface through at least one well provided with lateral openings extending into said hydrocarbon-bearing formation, transporting down said well and into the openings thereof a highly heatconductive material, depositing said material said well and said openings so that the material is in heattransferring proximity with said formation, said deposited material filling the well adjacent the hydrocarbon-bearing formation, and heating the material in the well to a temperature suicient to heat the surrounding hydrocarbon-bearing formation adjacent the well, said heating being carried out by positioning heating means in the Well in contact with the highly heat conductive material in the well whereby heat is conducted from said heating means through said heat conductive material to the hydrocarbon formation adjacent the well and is further oonducted through the material deposited within fractures or openings which extend laterally into said hydrooarbon formation.

2. A method of heating a hydrocarbon-bearing earth formation for the purpose of producing a hydrocarbon fluid therefrom, said method comprising the steps of establishing communication between the hydrocarbon-bearing formation and the ground surface through at least one well provided with lateral openings extending into said hydrocarbon-bearing formation, transporting down said well and into the openings thereof particles of a highly heat-'conductive material, depositing said particles in said well and said openings so that the particles are in heattransferring proximity with each other, said deposited particles filling the well adjacent the hydrocarbon-bearing formation, and heating the particulate material in the well to a temperature sufficient to heat the surrounding hydrocarbon-bearing formation adjacent the well, said heating being carried out by positioning heating mea-ns in the well in contact with the deposited particles in the well whereby heat is conducted from said heating means through said particulate material to the hydrocarbon formation adjacent the well and is further conducted through the particulate material deposited within the fractures or openings which extend laterally into said hydrocarbon formation.

3. A method of heating a hydrocrabon-bearing earth formation which is penetrated by at least two lwells for the purpose of producing a hydrocarbon uid therefrom, said method comprising the steps of establishing communication between the hydrocarbon-bearing formation and the ground surface through `at least two wells, one of said wells being provided with lateral openings extending into said hydrocarbon-bearing formation, transporting down `said well and into the openings thereof particles of a highly heat-conductive materia-l, depositing said particles in said well and said openings so that the particles are in heat-transferring Contact with each other, said deposited particles filling the well adjacent the hydrocarbon-bearing formation, and heating the particulate material in the Well to a temperature sufficient to heat the surrounding hydrocarbon-bearing formation adjacent the well, said heating being carried out by positioning heating means in the well in contact with the deposited particles in the well whereby heat is conducted from said heating means through said particulate material to the hydrocarbon formation adjacent the well and s further conducted through the particulate material deposited within the fractures or openings which extend laterally into said hydrocarbon formation.

4. A method of heating a hydrocarbon-bearing earth formation which is penetrated by at least two wells for the purpose of producing a hydrocarbon fluid therefrom, said method comprising the steps of establishing communication between the hydrocarbon-bearing formation and the ground surface through lat least two wells, one of said wells being provided with lateral openings extending into said hydrocarbon-bearing formation, pumping down said well and into the openings thereof a uid carrying particles of a highly heat-conductive material, depositing said particles in said well and said openings so that the particles are in heat-transferring contact with each other, said deposited particles filling the well adjacent the hydrocarbon-bearing formation, and heating the particulate material in the well to a temperature sufcient to heat Athe surrounding hydrocarbon-bearing formation adjacent the well, said heating being carried out by positioning heating means in the well in contact with the deposited particles in the well whereby heat is conducted from said heating means through said particulate material to the hydrocarbon formation adjacent the well and is lfurther conducted through the particulate material deposited within the fractures or openings which extend laterally into said hydrocarbon formation.

5. A method of heating a hydrocarbon-bearing earth formation which is penetrated by `at least two wells for the purpose of producing a hydrocarbon fluid therefrom, said method comprising the steps of establishing comareas/t munication between the hydrocarbon-bearing formation and the ground surface through at least two wells, creating lateral openings extending into said hydrocarbon-bearing formation in communication with one of said wells, transporting down said well and into the openings thereof particles of a highly heat-conductive material, depositing said particles in said well and said openings so that the particles are in heat-transferring contact with each other, said deposited particles filling the well adjacent the hydrocarbon-bearing formation, and heating the particulate material in the well to a temperature suflicient to heat the surrounding hydrocarbon-bearing formation adjacent the well, said heating being carried out by positioning heating means in the well in contact with the deposited particles in the well whereby heat is conducted from said heating means through said particulate material to the hydrocarbon formation adjacent the well and is further conducted through the particulate material deposited within the fractures or openings which extend laterally into said hydrocarbon form-ation.

6. A method -of heating a hydrocarbon-bearing earth formation which is penetrated by at least two -weils for the purpose of producing a hydrocarbon fluid therefrom, said method comprising the steps of establishing communication between the hydrocarbon-bearing formation and the ground surface through at least two wells, fracturing said hydrocarbon-bearing formation in communication with one of said wells'to create lateral yopenings therein, pumping down said well and into the openings thereof a uid carrying particles of a highly heat-conductive material, depositing said particles in said well and said openings so that the particles are in heatJtransferring contact with each other, said deposited particles filling the well adjacent the hydrocarbon-bearing formation, and heating the particulate material in the well to a temperature sufficient to heat the surrounding hydrocarbon-bearing formation `adjacent the well, said heating being carried out by positioning heating means in the well in contact with the depositedV particles in the well whereby heat is conducted from said heating means through said particulate material to the hydrocarbon formation adjacent the Wel-l and is further conducted through the particulate material deposited within the fractures or openings which extend laterally into said hydrocarbon formation.

7. A method of heating a hydrocarbon-bearing earth formation which is pene-trated by at least two wells for the purpose of producing a hydrocarbon fluid therefrom, said method comprising the steps of establishing communication between ithe hydrocarbon-bearing formation and the ground surface through at least two wells, direct5 tionally drilling lateral lopenings extending into said hydrocarbon-bearing formation in communication with one of said wells, pumping down said well and into the openings thereof a fluid carrying particles of a highly heatconductive material, depositing said particles in said well and said openings so that the particles are in heat-transferring contact with each other, said deposited particles filling the well adjacent the hydrocarbon-bearing formation, and heating the particulate material in the well to a temperature suicient to heat the surrounding hydrocarbon-bearing formation adjacent the well, said heating being carried out by positioning heating means in the well in contact with the deposited particles in the well whereby heat is conducted from said heating means through said particulate material lto the hydrocarbon formation adjacent the well and is further conducted through the particulate material deposited within the fractures or openings which `extend laterally into said hydrocarbon formation.

8. A method of heating a hydrocarbon-bearing earth formation `which is penetrated by at least two wells for the purpose of producing a hydrocarbon uid therefrom, said method comprising the steps of establishing communication between the hydrocarbon-bearing formation and the ground surface through at least two wells, creating lateral openings extending into said hydrocarbon-bearing formation in communication with one of said wells, pumping down said well and into the openings thereof a iiuid carrying particles of a highly heat-conductive material, depositing said particles in said well and said openings so that the particles are in heat-transferring Contact with each other, said deposited particles filling the well adjacent the hydrocarbon-bearing form-ation, installing heating means in the well in contact with the deposited particles in the well and in communication with a heat-generating power source at the top of the well, and heating the particulate material in the well to a temperature suf- -ticient to heat the surrounding hydrocarbon-bearing formation adjacent the well, said heat being conducted from said heating means through said particulate material to the hydrocarbon formation adjacent the well and is further conducted through the particulate material deposited within the fractures or openings which extend laterally into said hydrocarbon formation.

Jenks Nov. 27, 1956 Dixon Dec. 3l, 1957 

1. A PROCESS FOR IMPARTING A DURABLE SOLID RETAINING FINISH
 1. A METHOD OF HEATING A HYDROCARBON-BEARING EARTH FORMATION FOR THE PURPOSE OF PRODUCING A HYDROCARBON TO FIBROUS MATERIALS WHICH COMPRISES APPLYING THERETO, FROM A NON-AQUEOUS SOLVENT, AS A SOIL RETAINING FINISH FROM FLUID THEREFROM, SAID METHOD COMPRISING THE STEPS OF ESABOUT 2 TO ABOUT 5% OF AN ESSENTIALLY EQUIMOLECULAR TABLISHING COMMUNICATION BETWEEN THE HYDROCARBON-BEARING FORMATION AND THE GROUND SURFACE THROUGH AT LEAST AMOUNT OF A LONG CHAIN ANIONIC SURFACE ACTIVE COMPONENT AND A LONG CHAIN CATIONIC SURFACE ACTIVE COMPONENT, SAID ONE WELL PROVIDED WITH LATERAL OPENINGS EXTENDING INTO SAID HYDROCARBON-BEARING FORMATION, TRANSPORTING DOWN ANIONIC AND CATIONIC COMPONENT HAVING ABOUT 13 TO ABOUT 18 CARBON ATOMS, AND THEREAFTER DRYING AND CURING SAID SAID WELL AND INNTO THE OPENINGS THEREOF A HIGHLY HEATCONDUCTIVE MATERIAL, DEPOSITING SAID MATERIAL IN SAID FINISH ON SAID FIBROUS MATERIAL. WELL AND SAID OPENINGS SO THAT THE MATERIAL IS IN HEATTRANSFERRING PROXIMITY WITH SAID FORMATION, SAID DEPOSITED MATERIAL FILLING THE WELL ADJACENT THE HYDROCARBON-BEARING TORMATION, AND HEATING THE MATERIAL IN THE WELL TO A TEMPERATURE SUFFICIENT TO HEAT THE SURROUNDING HYDROCARBON-BEARING FORMATION ADJACENT THE WELL, SAID 